Split memory bank

ABSTRACT

A split memory bank may comprise a number of memory matrices forming a memory bank and a shift register in which the shift register physically separates the matrices. An integrated circuit may comprise a number of shift registers and a plurality of memory matrices forming a memory bank in which the matrices are spatially separated by the shift register. An integrated printhead may comprise a number of memory banks each comprising a plurality of memory matrices and a number of shift registers in which each shift register spatially separates a number of the matrices.

BACKGROUND

Erasable Programmable Read-Only memory (EPROM) is used in a number ofenvironments to maintain memory even when power is not provided to thememory. In integrated printhead (IPH) cartridges, an EPROM is placed onor in a printhead die. As storage requirements increase, area occupiedby the EPROM or memory bits also increases.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate venous examples of the principlesdescribed herein and are a part of the specification. The illustratedexamples are given merely for illustration, and do not limit the scopeof the claims.

FIG. 1 is a diagram of an EPROM bank design for storing and maintainingdata on an integrated printhead.

FIG. 2 is a diagram of an EPROM bank design for storing and maintainingdata on an integrated printhead according to one example of theprinciples described herein.

FIG. 3 is a perspective view of an integrated print cartridgeincorporating an integrated print head and EPROM bank of FIG. 2according to one example of the principles described herein.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements.

DETAILED DESCRIPTION

As mentioned above, as the amount of memory bits used to store data onan integrated printhead (IPH) increases, so does the footprint or Sireal estate. It has been determined that historically the memory bitsused to store data on an IPH doubles around every year or two. An EPROMis generally made up of a 64-bit EPROM bank with, for example, the bankbeing divided among 2 EPROM 4×8 matrices. A shift register may also beprovided to shift, by one position, the bit array stored in it.Electrical connections between the individual EPROM matrices and theshift register add to the footprint of the EPROM bank as a whole.

The present specification describes a split memory bank comprising anumber of memory matrices forming a memory bank and a shift register inwhich the shift register physically separates the matrices. In oneexample, the memory may be an EPROM such that a split EPROM bankcomprises two EPROM matrices physically separated by a shift register.

The present specification further describes an integrated circuitcomprising a number of shift registers and a plurality of memorymatrices forming a memory bank in which the matrices are spatiallyseparated by the shift register. In one example, the memory may be EPROMsuch that the integrated circuit comprises a number of shift registersand a plurality of EPROM matrices forming an EPROM bank, in which theEPROM matrices are spatially separated by the shift register.

Still further, the present specification describes an integratedprinthead comprising a number of memory banks each comprising aplurality of memory matrices and a number of shift registers in whicheach shift register spatially separates a number of the matrices. In oneexample, the memory may be EPROM such that an integrated printheadcomprising a number EPROM banks each comprising a plurality of EPROMmatrices, and a number of shift registers, in which each shift registerspatially separates a number of the EPROM matrices.

As used in the present specification and in the appended claims, theterm “erasable programmable read-only memory (EPROM)” meant to beunderstood broadly as any programmable read-only memory that may beretains its data when its power supply is switched off. In one example,the EPROM may be an erasable programmable read-only memory, anelectrically erasable programmable read-only memory, or any other typeof non-volatile memory that is electrically programmable.

Additionally, as used in the present specification and in the appendedclaims, the term “matrix” is meant to be understood broadly as any arrayof elements arranged in rows and columns that can store data. In oneexample, the array of elements in the matrix may be a 4×8 arrangementwith 4 rows and 8 columns. In another example, the matrix is an EPROMmatrix.

Further, as used in the present specification and in the appendedclaims, the term “memory bank” is meant to be understood broadly as anycombination of a number of memory matrices. In one example, a memorybank comprises two 4×8 memory matrices. In another example, the memorymatrices that make up the memory bank are EPROM matrices.

Even still further, as used in the present specification and in theappended claims, the term “a number of” or similar language is meant tobe understood broadly as any positive number comprising 1 to infinity;zero not being a number, but the absence of a number.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present systems and methods. It will be apparent,however, to one skilled in the art that the present apparatus, systemsand methods may be practiced without these specific details. Referencein the specification to “an example” or similar language means that aparticular feature, structure, or characteristic described in connectionwith that example is included as described, but may not be included inother examples.

An EPROM device on an integrated printhead (IPH) may comprise thoseelements show in FIG. 1. FIG. 1 is a diagram of an EPROM bank design(100) for storing and maintaining data on an integrated printhead. TheEPROM design shown in FIG. 1 comprises at least two EPROM matrices (110,115) and a multiplexing signal generator made of shift registers (105).The EPROM design (100) further comprises a number of lines (120)electrically connecting the EPROM matrices (110, 115) and a shiftregister (105) together. Although the memory bank design shown in FIG. 1is described as an EPROM memory bank (100), the memory bank may be anytype of memory storage as defined in the present description and is notnecessarily limited to EPROM technology. EPROM memory bank being onlyone example, for convenience, the present description will use an EPROMmemory bank as merely an example and is not meant to limit thedescription in any way.

In order to write and read from a specific EPROM matrix (110, 115), theshift register (105) selects a certain row select (125) and a certaincolumn select (130) on one of the two EPROM matrices (110, 115). In theexample show in FIG. 1, the shift register connects to each of the EPROMmatrices (110, 115) using two sets (135, 140) of 8 lines from among thenumber of lines (120); a first set (135) as output from the columnselect (130) on the shift register (105) and the other set (140) asoutput from the row select (125) on the shift register (105). Theselines separate to connect to the inputs of the individual EPROM matrices(110, 115). The different EPROM matrices (110, 115) of FIG. 1 areaccessed via this cascade method where the shill register (105) sendsall electrical lines down to the EPROM matrices (110, 115) with theelectrical lines cascading away from the group of lines when they are toconnect with an input of one of the EPROM matrices (110, 115). Thisdesign has all electrical lines emanating from the shift register (105)thereby occupying the maximum amount of space next to the EPROM bankdesign (100) as possible with electrical lines.

FIG. 2 is a diagram of an EPROM bank design (200) for storing andmaintaining data on an integrated printhead according to one example ofthe principles described herein. The EPROM design (200) comprises ashift register based multiplexing signal generator (205) physicallyseparating two EPROM matrices (210, 215). In one example, the EPROM bankcomprises two 4×8 EPROM matrices. In this example, the EPROM bank is a64-bit EPROM bank: two 32 bit EPROM matrices (210, 215). In one example,the EPROM design (200) comprises as single shift register (205).

Although, FIG. 2 shows an EPROM design (200) with an EPROM bankcomprising two 4×8 EPROM matrices (210, 215) and a single shift register(205), other configurations may exist. In one example, the EPROMmatrices (210, 215) may contain smaller or larger quantities of bitssuch that the number of rows and columns are reduced or increased beyondthe 4×8 example provided herein. Additional shift registers (205) andEPROM matrices may also be added to the EPROM design (200). In oneexample, a number of EPROM banks designs (200) depicted in FIG. 2 may becommunicatively coupled to each other and placed on an integratedprinthead (IPH). The design (200) depicted in FIG. 2, therefore, ismerely an example and other examples may exist without going beyond theprinciples described herein.

The placement of the shift register (205) between a first EPROM matrix(210) and a second EPROM matrix (215) provides for a number ofadvantages. Such a placement of the shift register (205) between a firstEPROM matrix (210) and a second EPROM matrix (215) provides for lessarea displaced on the SI chip. Specifically, unlike FIG. 1, theconnecting electrical lines between the shift register (205) and theEPROM matrices (210, 215) amounts to a 12 line depth from the outputsand inputs of the devices. Specifically, the shift register (205) hastwo separate outputs (235, 240) from the row select (225) with bothoutputs (235, 240) comprising 4 lines. However, these two sets of 4lines run in opposite directions and run parallel to the shift register(205) and EPROM matrices (210, 215) such that the two sets of four linestake up the same amount of space and lie the same distance from thosedevices. Additionally, the column select output (230) comprises eightlines (245) that bifurcate into two sets of eight lines that runparallel to the output lines (235, 240) and connect with the EPROMmatrices (210, 215). This results in a total line depth of 12 lines fromthe shift register (205) and EPROM matrices (210, 215).

Compared to FIG. 1, this is a 25% reduction in routing lines andconsequently a 14% reduction in the width of the EPROM bank. Thisreduces the amount of footprint n the EPROM bank design and allowssmaller designs of devices incorporating this EPROM bank such as anintegrated printhead. This may further allow for devices thatincorporate larger numbers of EPROM banks as described in FIG. 2. Forexample, where a plurality of EPROM banks as described in FIG. 2 areconnected, the footprint reduction of the entire group of EPROM banksallows for an additional number of EPROM banks to be added to the groupwithout increasing the original footprint occupied by other designs suchas that depicted in FIG. 1. Consequently, larger amounts of memory bitsmay be placed on a device such as an integrated printhead and largeramounts of data may be stored thereon. Additional data may provide forthe ability to store various other types of data that may be used toprovide additional features and benefits for the integrated printheadand printer.

FIG. 3, is a perspective view of an integrated print cartridge (300)incorporating an integrated print head and EPROM bank of FIG. 2according to one example of the principles described herein. Theintegrated print cartridge (300) is more generally a fluid-jetprecision-dispensing device or fluid ejector structure that preciselydispenses fluid, such as ink. In one example, the integrated printcartridge (300) illustrated in FIG. 3 may be a single color inkcartridge for a fluid-jet printer. However, according to the principlesdescribed herein, the integrated print cartridge (300) may beimplemented in any of a variety of fluid cartridges or printheads withan on-board memory.

While the present description describes generally an inkjet-printingcartridge that ejects ink onto media, examples of the presentspecification may not be limited to only inkjet printing cartridges andassociated devices. In general, examples of the present specificationpertain to any type of fluid-jet precision-dispensing or ejectiondevices that dispense a fluid. In the present specification and in theappended claims, the term fluid is meant to be broadly interpreted asany substance that deforms under an applied force. Examples of fluids,therefore, comprise liquids and gases. A fluid-jet precision-dispensingdevice is a device in which printing, or dispensing, of the fluid inquestion is achieved by precisely printing or dispensing in accuratelyspecified locations, with or without making a particular image on thatwhich is being printed or dispensed on. Thus, for purposes ofexplanation, a print cartridge or ink cartridge will be described.However, it will be understood that any type of fluid or liquidcartridge may be used with the principles described herein.

According to one example, the integrated print cartridge (300) iscomprised of an ink reservoir (310), a fluid-jet die (320), a flexiblecable (330), conductive pads (340), and an integrated circuit (350). Theflexible cable (330) is adhered to two sides of the print cartridge(300) and contains traces that electrically connect the integratedcircuit (350) and fluid-jet die (320) with the conductive pads (340).

The integrated print cartridge (300) is installed into a cradle that isintegral to the carriage of a printer. When the integrated printcartridge (300) is correctly installed, the conductive pads (340) arepressed against corresponding electrical contacts in the cradle,allowing the printer to communicate with, and control the electricalfunctions of, the integrated print cartridge (300). For example, theconductive pads (340) allow the printer to access and write to theintegrated circuit (350).

The integrated circuit (350) comprises at least one EPROM bank (FIG. 2,200) as described in FIG. 2 that contains a variety of informationincluding the type of ink cartridge, the kind of ink contained in thecartridge, an estimate of the amount of ink remaining in the inkreservoir (310), calibration data, error information, the identificationof the integrated printhead, an analog serial number, and securityfeatures such as cyclic redundant check (CRC), among others. The printercan take appropriate action based on the information contained in theink integrated circuit (350), such as notifying the user that the inksupply is low or altering printing routines to maintain image quality.In the illustrated example, the integrated circuit (350) is shown as aseparate element that is distinct from the ink jet die (320). However,according to one example, the ink jet die (320) may contain the memoryin addition to the physical elements used to dispense the ink.

To create an image, the printer moves the carriage containing the inkcartridge over a piece of print medium. At appropriate times, theprinter sends electrical signals to the integrated print cartridge (300)via the electrical contacts in the cradle. The electrical signals passthrough the conductive pads (340) and are routed through the flexiblecable (330) to the fluid-jet die (320). The fluid-jet die (320) thenejects a small droplet of ink from the reservoir (310) onto the surfaceof the print medium. These droplets combine to form an image on theprint medium surface.

The specification and figures describe a split memory bank comprising ashift register interposed between a number of memory matrices. Theseparation of, for example, two memory matrices to which the shiftregister is communicatively coupled to allows for a smaller footprintfor the split memory bank as described above. This may also reduce theamount of materials used to form the split memory bank as well as reducethe total size of a computing device or other element incorporating thesplit memory bank described herein.

The preceding description has been presented to illustrate and describeexamples of the principles described. This description is not intendedto be exhaustive or to limit these principles to any precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching.

What is claimed is:
 1. A split memory bank comprising: a number ofmemory matrices forming a memory bank; and a shift register basedmultiplexing signal generator; in which the shift register basedmultiplexing signal generator physically separates the matrices, and inwhich the shift register based multiplexing signal generator comprises asingle group of 8 electrical connection outputs from a column select andin which that single group of 8 electrical connection outputs branch outinto two groups of 8 electrical connections running perpendicular to thesingle group of 8 electrical connection outputs and connecting tocorresponding column select inputs on the number of matrices.
 2. Thesplit memory bank of claim 1, in which the memory is an EPROM.
 3. Thesplit memory bank of claim 1, in which the matrices each comprisesmultiple rows and a double amount of columns to rows.
 4. The splitmemory bank of claim 1, in which the split memory bank is electricallycoupled to a number of memory banks.
 5. The split memory bank of claim1, in which the shift register based multiplexing signal generatorcomprises a single group of 8 electrical connection outputs from a rowselect and in which that single group of 8 electrical connection outputsbranch out into two groups of 4 electrical connections runningperpendicular to the single group of 8 electrical connection outputs andconnecting to corresponding row select inputs on the number of matrices.6. The split memory bank of claim 1, in which the shift basedmultiplexing signal generator register comprises two groups of 4electrical connection outputs from a row select and in which thosegroups of 4 electrical connection outputs connect to corresponding rowselect inputs on the number of matrices.
 7. The split memory bank ofclaim 1, wherein the shift register based multiplexing signal generatorcomprises one column select output, with a plurality of lines connectedto the one column select output bifurcating to run in oppositedirections to connect, respectively, with each of two different memorymatrices of the memory bank.
 8. The split memory bank of claim 1,wherein the shift register based multiplexing signal generator comprisestwo separate row select outputs, with a plurality of lines running fromeach row select output to a different one of the memory matrices.
 9. Thesplit memory bank of claim 8, wherein the shift register basedmultiplexing signal generator comprises one column select output, with aplurality of lines connected to the one column select output bifurcatingto run in opposite directions to connect, respectively, with each of twodifferent memory matrices of the memory bank, the lines from the columnselect output being parallel with the lines from the row select output.10. The split memory bank of claim 8, wherein the shift register basedmultiplexing signal generator comprises one column select output, with aplurality of lines connecting the one column select with each of twodifferent memory matrices of the memory bank, there being no more than12 lines between the shift register based multiplexing signal generatorand each of the memory matrices.
 11. An integrated circuit comprising: anumber of shift registers; and a plurality of memory matrices forming amemory bank; in which the matrices are spatially separated by the shiftregister, in which each shift register comprises a single group of 8electrical connection outputs from a row select and in which that singlegroup of 8 electrical connection outputs branch out into two groups of 4electrical connections running perpendicular to the single group of 8electrical connection outputs and connecting to corresponding row selectinputs on each matrix.
 12. The integrated circuit of claim 11, in whichthe memory is EPROM.
 13. The integrated circuit of claim 11, in whichthe matrices each comprise a number of rows and double the number ofcolumns to rows.
 14. The integrated circuit of claim 11, in which eachshift register comprises two groups of 4 electrical connection outputsfrom a row select and in which those groups of 4 electrical connectionoutputs connect to corresponding row select inputs on each matrix. 15.The integrated circuit of claim 11, wherein one of the number of shiftregisters comprises: one column select output, with a plurality of linesconnecting the one column select with each of two different memorymatrices of the memory bank, two separate row selected outputs, eachconnected to a different memory matrix of the memory bank.
 16. Anintegrated printhead comprising: a number of memory banks eachcomprising a plurality of memory matrices; and a number of shiftregisters; in which each shift register spatially separates a number ofthe matrices, in which each shift register comprises a single group of 8electrical connection outputs from a row select and in which that singlegroup of 8 electrical connection outputs branch out into two groups of 4electrical connections running perpendicular to the single group of 8electrical connection outputs and connecting to corresponding row selectinputs on each matrix.
 17. The integrated printhead of claim 16, inwhich the memory is EPROM.